<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript">
			while(true){
				var score=prompt("请输入成绩");
				if(score>=0 && score<=100)
					break;
				else{
					alert("请输入有效成绩");
				}
			}
			if(score>=60){
				alert("合格");
			}
			else{
				alert("不合格");
			}
			
		</script>
	</head>
	<body>
	</body>
</html>
